Nexus 5 Stuck in Airplane Mode

Alas, my Nexus 5 has decided to be a loner.  It turned airplane mode on by itself, and no longer offers me the choice of turning it on or off.  If I try to make a call it says, "Turn off airplane mode first," but then when I push the power button, instead of asking if I want airplane mode or power off, it just says, "Power off?"

Any ideas?

Thanks!